The present invention is based on a fuel injection valve and a method for assembling a fuel injection valve.
German Patent No. 39 43 005 describes an electromagnetically actuable fuel injection valve in which several disk-shaped elements are arranged in the seat region. Upon excitation of the magnetic circuit, a flat valve plate functioning as a flat armature is lifted away from a valve seat plate located opposite and coacting with it; together they form a plate valve element. Arranged upstream from the valve seat plate is a swirl element that imparts a circular rotary motion to the fuel flowing toward the valve seat. A stop plate limits the axial travel of the valve plate on the side opposite the valve seat plate. The valve plate is surrounded by the swirl element with a large clearance; the swirl element thus provides a certain guidance for the valve plate. Recessed in the swirl element on its lower end face are several tangentially extending grooves which proceed from the outer periphery and extend into a central swirl chamber. Because the swirl element rests with its lower end face on the valve seat plate, the grooves exist as swirl channels.
WO 96/11335 describes a fuel injection valve on whose downstream end is arranged a multiple-disk atomization extension with a swirl preparation function. This atomization extension is provided downstream from a disk-shaped guide element built into a valve seat support, and from a valve seat also on the valve seat support; an additional support element holds the atomization extension in a defined position. The atomization extension is embodied with two disks or four disks, the individual disks being manufactured from stainless steel or silicon. Conventional machining methods, such as electrodischarge machining, punching, or etching, are correspondingly used in the manufacture of the opening geometries in the disks. Each individual disk of the atomization extension is fabricated separately, after which, in accordance with the desired number of disks, all the disks of the same size are stacked onto one another to form the complete atomization extension. Assembly of the atomization extension is accomplished from the downstream, spray-discharge end of the valve. From this end, the guide element, valve seat element, atomization extension, and support element are introduced into the stepped passthrough opening of the valve seat support up to a stop. This entire component complex is retained in the valve seat support by the fact that an end region of the valve seat support is subsequently folded over by crimping or bending.
European Patent No. 0 616 663 describes a fuel injection valve in which a valve seat element can be inserted, in the spray-discharge direction, into an extension body that can be screwed onto the valve housing. The valve seat element rests on a shoulder of the extension body, and is thereby at least partially supported from below by the extension body. The extension body with the valve seat element in place is, however, screwed onto the valve housing against the spray-discharge direction until the valve seat element comes into contact against a swirl insert arranged upstream from it.
German Patent Application No. 196 07 288 describes in the so-called multilayer electroplating process for manufacturing orifice disks that are suitable, in particular, for use in fuel injection valves. This principle for manufacturing disks by multiple electroplating deposition of variously structured metals onto one another, resulting in an integral disk, is expressly incorporated herein by reference. Microelectroplating metal deposition in several planes, plies, or layers is also used to manufacture the atomization disks used here and incorporated according to the present invention.
The fuel injection valve according to the present invention has the advantage of yielding a very high atomization quality in a fuel that is to be sprayed out, as well as spray shaping that is configurable in highly variable fashion and adapted to the respective requirements (e.g. installation conditions, engine configurations, cylinder shapes, spark plug position). One of the consequences of using atomizer disks that are very easy to place in the fuel injection valve is that the exhaust emissions of an internal combustion engine equipped with corresponding fuel injection valves are reduced, and also that a decrease in fuel consumption is attained.
Particularly advantageously, the atomizer disk is manufactured by multilayer electroplating. Because of their metallic configuration, the atomizer disks are highly resistant to breakage and easily assembled. The use of multilayer electroplating allows a great deal of design freedom, since the contours of the opening regions (inlet regions, swirl channels, swirl chamber, outlet opening) in the atomizer disk can be selected without restriction. This flexible conformation is very advantageous especially by comparison with silicon disks, in which the contours achievable (truncated pyramids) are strictly defined based on the crystal axes.
Metal deposition offers a very wide selection of materials, especially by comparison with the manufacture of silicon disks. A large variety of metals, with their differing magnetic properties and hardnesses, can be utilized in the microelectroplating method used to manufacture the atomizer disks.
It is advantageous to embody the atomizer disk in the form of a swirl disk. It is particularly advantageous to construct the swirl disk, comprising three layers, by performing three electroplating steps for metal deposition. The swirl generation layer is constituted by one or more material regions that, because of their contouring and their geometrical position with respect to one another, yield the contours of the swirl chamber and the swirl channels. With the electroplating process, the individual layers are built up onto one another without joins or seams, so that they represent continuously homogeneous material. To that extent, the term xe2x80x9clayersxe2x80x9d is to be taken as an aid to understanding.
Advantageously, two, three, four, or six swirl channels are provided in the swirl disk. The material regions can possess very different shapes corresponding to the desired contouring of the swirl channels, e.g., can be strut-like or helical.
The method according to the present invention for assembling a fuel injection valve, has the advantage of particularly simple attachment of an atomizer disk to the downstream valve end. An atomizer disk can be securely mounted while dispensing with weld joins. The outer contour of a valve seat support partially forming a valve housing can be configured in particularly simple and compact fashion with a base region used to receive valve components.